1. SKA Science Measuring Variations in the Fundamental Constants with the SKA Steve Curran School of Physics School of Physics University of New South Wales

2. SKA Science To Earth Heavy element absorption Emission lines from the Quasar Lyman limit Hydrogen absorption due to galaxy Quasar Observed wavelength (Å) Lyman alpha forest DLA

3. SKA ScienceMotivation Optical studies (Webb et al. 2002, astro-ph/0210531) suggest that    = -0.57(0.10) x 10 -5 for 0.2< z abs < 3.7 Although Chand et al. 2004 (astro-ph/0401094) find no change over 0.4< z abs < 2.3

4. SKA Science Advantage of Radio Lines 21-cm Spin-Flip (HI) Line Transition Interaction of electron and proton magnetic fields 21 is proportional to  2 g p   That is, comparing radio and optical gives an order of magnitude the sensitivity of the purely optical comparisons. See Drinkwater et al., 1998, MNRAS 295, 457. Optical Transitions Interaction is Coulombic, so opt is proportional to (1 + 0.03  2 ) (Flambaum & Dzuba)

5. SKA Science Furthermore, using molecular lines… 1720  1612    2.6   g p 1720  1612    2.6   g p CO, HCO +, etc - 21  mm   2 g p OH (18 cm) – 1665  1667    -1.1   Also constraints from other OH (  6 cm) transitions – Chengalur & Kanekar, 2003, PRL 91, 241302. 1665  1667    -0.9   g p 1665  1667    -0.9   g p also – 1667  mm   -1.1   also – 1667  mm   -1.1   no g p

6. SKA Science  y/y = -1×10 -5  /   For a constant g p,  /   ~10 -6 can be measured for an individual cloud, thus decent statistics needed.  y =  2 g p  Currently  46 high z HI 21-cm absorbers 4 known redshifted mm/OH absorbers known High SKA resolution can verify upon which line-of-sight the absorption occurs

7. SKA Science All current constraints:, MNRAS 327, 1244

8. SKA Science With the SKA … After 1 hour at 1 km/s resolution Frequency range 0.1 – 25 GHz 0H z abs  16 HI z abs  13 CO, HCO +, HCN z abs  2.6  13 2.6 - 13 c.f. z abs < 0.7 for today’s HI/molecular comparisons! S rms ~ 0.2 mJy @ 200 MHz ~ 0.04 mJy @ 0.5 to 5 GHz ~ 0.01 mJy @ 25 GHz

9. SKA Science HI 21-cm Absorption  v  FWHM  10 km/s, S  0.3 Jy, after 1 hour N HI  2 - 50 x 10 14 T s /f cm -2 (3  ), z abs < 6. Currently 17/34 detected, T spin  10 4 K (f ~ 1) For  10 20 cm -2 (DLAs), T spin  10 5 K or f  10 -4 Detect HI in 87 known DLAs, plus those << 0.3Jy as well as gazillions of other absorbers T s  100 K (f ~ 1)  N HI ~10 17 cm -2 LLSs!

10. SKA Science Molecular Absorption  v  FWHM  10 km/s, S  0.1 Jy, after 1 hour N CO ~10 13 (z abs  3.6), N HCO+ ~ 10 10 (z abs  2.6) cm -2 N OH ~ 10 12 – 10 14 (0  z abs  16), T x =10 K @ z = 0  ƒ ~ 10 -4 per unit line-width BUT! From H 2 -bearing DLAs expect ƒ  10 -4 at z abs  2.6 Curran et al. 2004 (astro-ph/0311357) However, for the 4 known molecular absorbers ƒ = 0.3 to 1 (from mm, Wiklind & Combes) and N OH ~ 1 – 12 x 10 15 cm -2  Search for non-optically selected objects

11. SKA Science Summar y Detect HI absorption in > 1/4 of all DLAs as well as in all other absorbers with N HI  10 17 cm -2, i.e. a large sample of absorbers of known redshifts Large band-width & field of view   500 MHz & ~ 200 square degrees SKA ideal for surveys unbiased by dust extinction for HI & OH (and possibly high-z mm) absorption SKA will vastly increase number of HI/OH absorbers yielding redshifts with which to search for mm-lines (N OH  30 x N HCO+ ) with ALMA  Accurate constraints of  various combinations of  g p,   nnnn